1. Field of the Invention
The present invention relates to a process for the preparation of stable iodate-exchanged synthetic hydrotalcite with zero effluent discharge.
More particularly, the invention relates to a process for utilization of alkaline effluent generated in the said iodate exchange process to regenerate iodate salt from elemental iodine thereby making the process zero effluent discharge hence more economical.
2. Background and Prior Art of the Invention
Iodine is a very important trace element necessary in the biosynthesis of thyroid hormones. Iodine is required for developing and maintaining healthy body. There are well known Iodine Deficiency Disorders like Goiter and Cretinism. The edible salt is chosen as a vehicle in the provision of iodine because of its uniform consumption and availability to all segments of population independent of social or economic status. In order to deliver adequate amount of iodine to the consumer while avoiding the unnecessary excess addition of iodizing agent in salt that is normally done to compensate for losses, it is of paramount importance that a stable iodizing agent should be used.
The iodate-exchanged synthetic hydrotalcite is known to be useful as an iodizing agent.
Reference may be made to Patent publication No. WO/2006/067798 dated 29 Jun., 2006, Ghosh, P. K. et al. wherein the prior art on salt iodization and stability of iodine in iodized salt are cited.
Reference may be made to Republic of South Africa Patent No. 20004598, Kulkami, S. M. and Pramanik, A. wherein the preparation of stable iodized salt through intercalation of iodate anion in layered double hydroxide is being disclosed. Although excess amount of potassium iodate is taken for the above purpose no mention is made of the fate of the residual iodate-containing effluent.
Reference may be made to Indian Patent Application No. 1219/DEL/2004 dated on 30Jun. 2004 (corresponding WO2006/003669 and US20060003024), Ghosh, P. K. et al. wherein a stable form of iodizing agent prepared through ion-exchange of iodate anion in synthetic hydrotalcite clay is disclosed. The process involves calcination of SHT, treatment of the calcined SHT with potassium iodate solution, filtering of the mass to obtain SHT-iodate and liquid effluent. It is stated therein that a part of the potassium iodate remains in the effluent and, furthermore, that all of the potassium ion originally present in the potassium iodate is also present in the effluent but there is no mention of the fate of the effluent.
Reference may also be made to Patent publication No. WO/2006/067798 dated 29 Jun., 2006, Ghosh et al. wherein the preparation of 5:1 (mole ratio) of iodide salt to iodate salt is obtained by treating elemental iodine with alkali solution.
Reference may also be made to Indian Patent Application No: 0479/DEL/2003, Ghosh et al. wherein an improved process of preparation of potassium iodate from potassium iodide is disclosed.
Reference may also be made to Chinese patent No: CN 1861091, Xia, Meisheng et al. wherein the process for preparation of new hydrotalcite formulations for iodine supplement is disclosed.
In view of the above cited prior art, the inventors of this application understood the need for a process for the preparation of an oxidizing agent with zero effluent discharge which obviates the drawbacks of the prior art.